INSTRUMENTATION FOR ENGINEERING MEASUREMENTS Second Edition
JAMES W. DALLY University of Maryland
WILLIAM F. RILEY KENNETH G. McCONNELL Iowa State University
JOHN WILEY & SONS, INC. New York • Chichester • Brisbane
• Toronto
•
Singapore
CONTENTS
LIST OF SYMBOLS CHAPTER 1 APPLICATIONS OF ELECTRONIC INSTRUMENT SYSTEMS 1.1 INTRODUCTION 1.2 THE ELECTRONIC INSTRUMENT SYSTEM 1.3 ENGINEERING ANALYSIS 1.4 PROCESS CONTROL 1.4.1 PROCESS CONTROL DEVICES 1.5 EXPERIMENTAL ERROR 1.5.1 ACCUMULATION OF ACCEPTED ERROR 1.5.2 IMPROPER FUNCTIONING OF INSTRUMENTS 1.5.3 EFFECT OF THE TRANSDUCER ON THE
1.6 1.7
R2 CHAPTER 2.1 2.2 2.3 2.4
2.5 2.6 2.7 2.8 2.9
xvii
01 01 02 03 04 06 12 13 14
PROCESS 1.5.4 DUAL SENSITIVITY ERRORS 1.5.5 OTHER SOURCES OF ERROR MINIMIZING EXPERIMENTAL ERROR SUMMARY REFERENCES EXERCISES
15 17 18 19 20 20 21
ANALYSIS OF CIRCUITS INTRODUCTION AND DEFINITIONS BASIC ELECTRICAL COMPONENTS KIRCHHOFF'S CIRCUIT LAWS DIODES, TRANSISTORS, AND GATES 2.4.1 DIODES 2.4.2 TRANSISTORS 2.4.3 GATES DC CIRCUITS PERIODIC FUNCTIONS AC CIRCUITS 2.7.1 IMPEDANCE FREQUENCY RESPONSE FUNCTION SUMMARY REFERENCES EXERCISES
CHAPTER 3 ANALOG RECORDING INSTRUMENTS 3.1 INTRODUCTION 3.2 GENERAL CHARACTERISTICS OF RECORDING INSTRUMENTS 3.3 VOLTMETERS FOR STEADY-STATE MEASUREMENTS 3.3.1 D'ARSONVAL GALVANOMETER 3.3.2 AMMETER 3.3.3 DC VOLTMETERS 3.3.4 VOLTMETER LOADING ERRORS 3.3.5 AMPLIFIED VOLTMETERS 3.3.6 POTENTIOMETRIC VOLTMETERS 3.4 VOLTMETERS FOR SLOWLY VARYING SIGNALS 3.4.1 STRIP-CHART RECORDERS 3.4.2 X-Y RECORDERS 3.5 VOLTMETERS FOR RAPIDLY VARYING SIGNALS 3.5.1 OSCILLOGRAPH RECORDERS 3.5.2 TRANSIENT RESPONSE OF GALVANOMETERS 3.5.3 PERIODIC SIGNAL RESPONSE OF GALVANOMETERS 3.5.4 OSCILLOSCOPES 3.5.5 MAGNETIC TAPE RECORDERS 3.6 SUMMARY REFERENCES EXERCISES CHAPTER 4 4.1 4.2 4.3 4.4 4.5
4.6 4.7 4.8 4.9 4.10 4.11 4.12
DIGITAL RECORDING SYSTEMS INTRODUCTION DIGITAL CODES CONVERSION PROCESSES DIGITAL-TO-ANALOG CONVERTERS ANALOG-TO-DIGITAL CONVERTERS 4.5.1 SUCCESSIVE-APPROXIMATION METHOD 4.5.2 INTERGRATION METHOD 4.5.3 PARALLEL OR FLASH METHOD DATA DISTRIBUTION 4.6.1 BUS STRUCTURES INTERFACES DIGITAL VOLTMETERS DATA-LOGGING SYSTEMS DATA-ACQUISITION SYSTEMS PC-BASED DATA-ACQUISITION SYSTEMS DIGITAL OSCILLOSCOPES
PIEZOELECTRIC-TYPE PRESSURE TRANSDUCER MINIMIZING ERRORS IN TRANSDUCERS 8.6.1 DUAL SENSITIVITY 8.6.2 ZERO SHIFT WITH TEMPERATURE CHANGE 8.6.3 BRIDGE BALANCE 8.6.4 SPAN ADJUST 8.6.5 SPAN CHANGE WITH TEMPERATURE FREQUENCY RESPONSE OF TRANSDUCERS 8.7.1 RESPONSE OF A FORCE TRANSDUCER TO A TERMINATED RAMP FUNCTION 8.7.2 RESPONSE OF A FORCE TRANSDUCER TO A SINUSOIDAL FORCING FUNCTION CALIBRATION OF TRANSDUCERS SUMMARY REFERENCES EXERCISES
285 286 288 289 290
DISPLACEMENT, VELOCITY, AND ACCELERATION MEASUREMENTS INTRODUCTION THE SEISMIC TRANSDUCER MODEL
293 293 294
275 276 277 279 280 280 280 280 282
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CONTENTS
9.3
9.4
9.5 9.6
9.7 9.8 9.9
9.10 9.11 9.12
9.13
9.14
9.15
DYNAMIC RESPONSE OF THE SEISMIC MODEL 9.3.1 SINUSOIDAL EXCITATION 9.3.2 TRANSIENT EXCITATIONS SEISMIC MOTION TRANSDUCERS 9.4.1 SEISMIC DISPLACEMENT TRANSDUCERS 9.4.2 SEISMIC VELOCITY TRANSDUCERS 9.4.3 SEISMIC ACCELERATION TRANSDUCERS PIEZOELECTRIC FORCE TRANSDUCERS PIEZOELECTRIC SENSOR CIRCUITS 9.6.1 CHARGE SENSITIVITY MODEL 9.6.2 VOLTAGE-FOLLOWER CIRCUIT 9.6.3 CHARGE-AMPLIFIER CIRCUIT 9.6.4 BUILT-IN VOLTAGE FOLLOWERS RESPONSE OF PIEZOELECTRIC CIRCUITS TO TRANSIENT SIGNALS ACCELEROMETER CALIBRATION DYNAMIC CALIBRATION OF FORCE TRANSDUCERS 9.9.1 FORCE TRANSDUCER CALIBRATION BY IMPACT OVERALL SYSTEM CALIBRATION SOURCES OF ERROR WITH PIEZOELECTRIC TRANSDUCERS DISPLACEMENT MEASUREMENTS IN A FIXED REFERENCE FRAME 9.12.1 DISPLACEMENT MEASUREMENTS WITH RESISTANCE POTENTIOMETERS 9.12.2 DISPLACEMENT MEASUREMENTS WITH MULTIPLE-RESISTOR DEVICES 9.12.3 PHOTOELECTRIC DISPLACEMENT TRANSDUCERS OPTICAL DISPLACEMENT MEASUREMENTS 9.13.1 OPTICAL TRACKER SYSTEM 9.13.2 VIDEO CAMERA MOTION ANALYSIS VELOCITY MEASUREMENTS 9.14.1 LINEAR-VELOCITY MEASUREMENTS 9.14.2 ANGULAR-VELOCITY MEASUREMENTS 9.14.3 LASER-DOPPLER SYSTEM SUMMARY REFERENCES EXERCISES
CHAPTER 10 ANALYSIS OF VIBRATING SYSTEMS 356 10.1 INTRODUCTION 356 10.1.1 TEMPORAL MEAN 358 10.1.2 TEMPORAL MEAN SQUARE AND ROOT MEAN SQUARE 358 10.2 SINUSOIDAL SIGNAL ANALYSIS 358 10.3 CHARACTERISTICS OF SIGNALS 3 61 10.3.1 PERIODIC SIGNALS 362 10.3.2 TRANSIENT SIGNALS 363 10.3.3 RANDOM SIGNALS 366 10.4 LUMPED MASS-SPRING VIBRATION MODELS 368 10.4.1 UNDAMPED NATURAL FREQUENCY AND MODE SHAPE 369 10.4.2 FORCED VIBRATION RESPONSE (DIRECT SOLUTION) 370 10.4.3 FORCED VIBRATION RESPONSE (MODAL SOLUTION) 370 10.5 CONTINUOUS VIBRATION MODELS 373 10.5.1 FUNDAMENTAL EQUATION OF MOTION 373 10.5.2 STEADY-STATE MODAL SOLUTION 374 10.6 THE LINEAR INPUT-OUTPUT MODEL 376 10.6.1 IMPULSE RESPONSE 377 10.6.2 RANDOM INPUT-OUTPUT RELATIONSHIPS 379 10.7 BASICS OF A DIGITAL FREQUENCY ANALYZER 380 10.7.1 TIME SAMPLING PROCESS 380 10.7.2 CONVOLUTION 381 10.7.3 FILTER LEAKAGE 385 10.7.4 BLOCK DIAGRAM 387 10.8 USING A DIGITAL FREQUENCY ANALYZER 387 10.8.1 RELATIONSHIPS FOR FREQUENCY ANALYZERS 388 10.8.2 FILTER CHARACTERISTICS 390 10.8.3 FOUR COMMON WINDOW FUNCTIONS 392 10.8.4 UNCERTAINTY IN THE MAGNITUDE OF SPECTRAL LINES 394 10.8.5 SUMMARY OF WINDOW USE 395 10.9 ACCELEROMETER CROSS-AXIS SENSITIVITY 396 10.9.1 SINGLE ACCELEROMETER CROSS-AXIS COUPLING MODEL 396 10.9.2 TRIAXIAL ACCELEROMETER MODEL 397 10.9.3 CORRECTING ACCELERATION VOLTAGE READINGS 397
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CONTENTS
10.9.4
10.10
10.11
APPLICATION TO MODAL ANALYSIS SIGNALS 10.9.5 CROSS-AXIS RESONANCE FORCE TRANSDUCER-STRUCTURE INTERACTION 10.10.1 GENERAL TWO-DEGREE-OF-FREEDOM FORCE TRANSDUCER MODEL SUMMARY REFERENCES EXERCISES
399 399 400 401 406 408 409
CHAPTER 11 TEMPERATURE MEASUREMENTS 412 11.1 INTRODUCTION 412 11.2 EXPANSION METHODS FOR MEASURING TEMPERATURE 415 11.3 RESISTANCE THERMOMETERS 416 11.3.1 RESISTANCE TEMPERATURE DETECTORS (RTDS) 417 11.3.2 RTDS AND THE WHEATSTONE BRIDGE 420 11.3.3 THERMISTORS 424 11.4 THERMOCOUPLES 428 11.4.1 PRINCIPLES OF THERMOCOUPLE BEHAVIOR 430 11.4.2 THERMOELECTRIC MATERIALS 434 11.4.3 REFERENCE IUNCTION TEMPERATURE 437 11.4.4 FABRICATION AND INSTALLATION PROCEDURES 439 11.4.5 RECORDING INSTRUMENTS FOR THERMOCOUPLES 442 11.4.6 NOISE SUPPRESSION IN THERMOCOUPLE CIRCUITS 444 11.5 INTEGRATED-CIRCUIT TEMPERATURE SENSORS 444 11.6 DYNAMIC RESPONSE OF TEMPERATURE SENSORS 446 11.7 SOURCES OF ERROR IN TEMPERATURE MEASUREMENTS 449 11.8 CALIBRATION METHODS 453 11.9 RADIATION METHODS (PYROMETRY) 454 11.9.1 PRINCIPLES OF RADIATION 454 11.9.2 THE OPTICAL PYROMETER 456 11.9.3 INFRARED PYROMETERS 458 11.9.4 PHOTON DETECTOR TEMPERATURE INSTRUMENTS 460 11.10 SUMMARY 463 REFERENCES 465 EXERCISES 466
CONTENTS
CHAPTER 12 12.1 12.2
12.3
12.4 12.5
12.6 12.7
12.8
FLUID FLOW MEASUREMENTS INTRODUCTION FLOW VELOCITY (INSERTION-TYPE TRANSDUCERS) 12.2.1 PITOT TUBE (INCOMPRESSIBLE FLOW) 12.2.2 PITOT TUBE (COMPRESSIBLE FLOW) 12.2.3 HOT-WIRE AND HOT-FILM ANEMOMETERS 12.2.4 DRAG-FORCE VELOCITY TRANSDUCERS 12.2.5 CURRENT METERS 12.2.6 TURBINE FLOW METERS 12.2.7 VORTEX-SHEDDING TRANSDUCERS FLOW RATES IN CLOSED SYSTEMS BY PRESSURE-VARIATION MEASUREMENTS 12.3.1 VENTURI METER 12.3.2 FLOW NOZZLE 12.3.3 ORIFICE METER 12.3.4 ELBOW METER FLOW RATES IN PARTIALLY CLOSED SYSTEMS FLOW RATES IN OPEN CHANNELS FROM PRESSURE MEASUREMENTS 12.5.1 SLUICEGATE 12.5.2 WEIRS COMPRESSIBLE FLOW EFFECTS IN CLOSED SYSTEMS OTHER FLOW-MEASUREMENT METHODS FOR CLOSED SYSTEMS 12.7.1 CAPILLARY FLOW METER 12.7.2 POSITIVE-DISPLACEMENT FLOW METERS 12.7.3 HOT-FILM MASS FLOW TRANSDUCERS 12.7.4 LASER VELOCIMETRY SYSTEMS SUMMARY REFERENCES EXERCISES
CHAPTER 13 STATISTICAL METHODS 13.1 INTRODUCTION 13.2 CHARACTERIZING STATISTICAL DISTRIBUTIONS 13.2.1 GRAPHIC REPRESENTATIONS OF THE DISTRIBUTION 13.2.2 MEASURES OF CENTRAL TENDENCY 13.2.3 MEASURES OF DISPERSION 13.3 STATISTICAL DISTRIBUTION FUNCTIONS 13.3.1 GAUSSIAN DISTRIBUTION 13.3.2 WEIBULL DISTRIBUTION
